The present disclosure relates to refrigeration compressors. More particularly, it relates to hermetic reciprocating piston compressors. A variety of refrigerant compressor configurations are in common use. Among these configurations are: screw compressors; scroll compressors; and reciprocating piston compressors.
In closed-drive or hermetic compressors, an electric motor is contained within the compressor's case. In such compressors, the crankshaft is fully internal to the case and does not need to be sealed relative to the case. In other (open-drive) compressors, the motor (whether electric or other) is external to the case and the crankshaft penetrates the case. An external portion of the crankshaft is mechanically coupled to the motor. In such situations, a portion of the crankshaft penetrating the case must be sealed to the case.
Two particular subfields of refrigeration systems wherein reciprocating compressors are often used are: as central compressors for distributed retail display cabinets; and in transport refrigeration systems (e.g., truck, trailer, and cargo container refrigeration systems). An exemplary state of the art transport refrigeration system uses a diesel-electric hybrid system to electrically power a reciprocating piston compressor which uses R-404A HFC refrigerant. More recently, it has been proposed to use carbon dioxide-based refrigerants (e.g., R-744) due to concerns regarding the environmental impact of HFCs.